Method of forming a hole in the wall of a hollow workpiece



Sept. 13, 1966 K. w. KLINKSIEK METHOD OF FORMING A HOLE IN THE WALL OF A HOLLOW WORKPIECE 3 Sheets-Sheet 1 Filed April 24, 1963 INV E NTOR KARL W- KLINKSIEK /AL mv Sept. 13, 1966 K. W. KLlNKSlEK METHOD OF FORMING A HOLE IN THE WALL OF A HOLLOW WORKPIECE Filed April 24, 1965 5 Sheets-Sheet 23 FIG. 2

INVENTOR KARL W. KLINKSIEK Sept. 13, 1966 METHOD OF FORMING A HOLE IN THE WALL OF A HOLLOW WORKPIECE 5 Sheets-Sheet 5 Filed April 24, 1963 INV E NTOR FIG. 8

KARL W. KLINKSIEK BY Q United States Patent Office 3,271,988 Patented Sept. 13, 1966 METHOD OF FORMING A HOLE IN THE WALL OF A HOLLOW WORKPIECE Karl W. Klinksiek, Richmond Heights, Mo., assignor to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Filed Apr. 24, 1963, Ser. No. 275,807 14 Claims. (Cl. 72325) The present invention relates to fluid pressure cylinders and more particularly to an improved method and apparatus for forming fluid flow passage means in the wall of the fluid pressure cylinder.

A fluid pressure cylinder for a hydraulic system, such as a master cylinder, is provided with a vent or pressure fluid compensation port hole or port extending through the cylinder Wall to provide pressure fluid communication between the cylinder bore and the pressure fluid reservo1r chamber when the master cylinder piston and primary cup assembly are in their retracted positions in said cylinder bore. The compensation port hole not only provides for fluid pressure equalization between the reservoir chamber and the pressure generating portion of the cylinder bore when the piston and cup assembly is in the retracted position but also serves to provide a path for supercharging pressure fluid flow from the reservoir chamber into the pressure generating portion of the cylinder bore. Since the primary sealing cup of the master cylinder is moved back and forth across the compensating port hole by the piston during operation of the master cylinder, the radially inner mouth of the compensation port hole must be relatively small in diameter, as Well as free of burrs and sharp edges, in order to avoid the undesirable feature of extrusion of the cup into the compensation port hole and excessive cup cutting and wear. Also, the compensation port hole must be accurately located relative to the piston and primary cup assembly so as to avoid excessive lost motion of the piston and cup assembly during the protractile pressure generating stroke thereof as well as to insure open pressure fluid communication between the reservoir chamber and the pressure generating portion of the cylinder bore when the piston and cup assembly return to their retracted positions at the end of the retractile stroke thereof.

In the past, it has been common practice to form the compensation port hole in a master cylinder by inserting drills through the filler cap opening for the reservoir chamber and through the reservoir chamber so as to drill from the outside radially inwardly through the cylinder wall. This drilling operation was usually performed in two steps in order to reduce drill breakage. First, a drill of relatively large diameter was disposed in the reservoir chamber through the filler cap opening and used to drill only partially through the cylinder wall to provide a recess of predetermined depth. Then a relatively smaller drill having a size corresponding to the desired size of the compensation port hole was inserted into the recess for drilling through the remaining portion of the cylinder wall. By way of example, one typical port hole has a diameter of about .027 of an inch.

Although the small fragile drill was used to drill through only a portion of the cylinder Wall, drill breakage nevertheless was an undesirable feature and a serious manufacturing problem, and it Was also diflicult to maintain such small drills in sharpened condition. An additional undesirable feature was that the above drilling method produced a sharp edge at the inner mouth of the port which was necessarily removed by a special peening operation to bevel or smoothly round the inner mouth or edge of the compensating port hole. A further undesirable feature was that since the small drill Was employed in the operation following the formation of the recess, even a slight misalignment of the recess, as a result of the larger drill walking during its use, would cause the compensating port hole to be displaced or mlsaligned from its intended location. Therefore, the resulting misalignment of the compensating port hole beyond the predetermined manufacturing limits, as a result of either the large or small drill walking, resulted in unusable or scrap parts.

It is an object of the present invention to provide novel method, and/ or apparatus, for forming a passageway extending through the cylinder wall of a fluid pressure cylinder in which the abovernentioned undesirable features are obviated.

Another object is to provide a novel method of forming a fluid flow passageway through the Wall of a fluid pressure cylinder whereby the passageway is accurately located therein.

Another object is to provide novel method for perforating the Wall of a fluid pressure cylinder to provide a fluid passageway therethrough having a smooth, rounded mouth at the inner side of the cylinder wall.

Another object is to provide a novel punching apparatus for use in forming an opening in the wall of a master cylinder which, in a single operation, perforates the wall to form the opening, and smoothes the mouth of the opening on the bore side of the cylinder.

Still another object is to provide a novel punching apparatus for use in forming an opening in the wall of a fluid pressure cylinder and which is relatively simple in construction and use and whereby economies of manufacture are obtained.

These and other objects and advantages of the present invention will be apparent from the following detailed description, reference being had to the accompanying drawings wherein like numerals refer to like parts.

In the drawings:

FIG. 1 is a cross-sectional view showing a master cylinder housing, in one stage of its fabrication, disposed on a punching apparatus of the present invention, the punching apparatus being shown in its unactuated condition,

FIG. 2 is a cross-sectional view similar to FIG. 1 but with the punching apparatus in an actuated condition,

FIG. 3 is a fragmentary sectional view of a fully assembled master cylinder assembly utilizing the master cylinder housing of FIGS. 1 and 2 in its completed form,

FIG. 4 is an enlarged bottom view, partly in section, of the punching element of the punch apparatus shown in FIGS. 1 and 2,

FIG. 5 is a top elevational view of the punching element 'as shown in FIG. 4,

FIGS. 6 and 7 are left-side and bottom views, respectively, of the end portion of the punch actuating member of the punching apparatus shown in FIGS. 1 and 2,

FIG. 8 is an enlarged fragmentary view showing in cross section a completed compensating port hole through the wall portion of the master cylinder of FIG. 2, and

FIG. 9 is an enlarged fragmentary view in cross section illustrating a modification of the present invention.

Briefly, the present invention provides a novel method of forming an opening in the side wall of a bore in a fluid pressure cylinder which, in one form, includes the step of perforating the side wall of the cylinder bore from the bore side of the cylinder. The invention also provides a novel perforating apparatus for forming an opening in the side wall of a fluid pressure cylinder. In one form, the apparatus includes a sleeve member adapted for disposition in the bore of a fluid pressure cylinder, a perforating element movable in the sleeve member for perforating engagement with the side wall of the cylinder bore, and driving means movable in the sleeve member for urging the perforating element into perforating engagement with the side wall of the cylinder bore to provide an opening therein.

Referring now to the drawings, the numeral designates a master cylinder housing which is shown in FIGS. 1 and 2 in different stages of its fabrication. In FIG. 3 there is shown a portion of a completed master cylinder assembly utilizing the master cylinder housing after it has been fully fabricated in accordance with the present invention. The housing 10 includes a master cylinder 12 having a bore 14 and a pressure fluid reservoir 16. A Wall portion of the master cylinder, indicated at 12a, partitions the bore 14 from the reservoir 16. As shown in FIGS. 1 and 2, the housing 10 is also provided with a fluid outlet port 17 and a rectangular mounting flange 18 having openings 19 (shown in phantom) which are adapted to receive bolts (not shown) for mounting the completed master cylinder assembly for operation in a fluid pressure system.. The reservoir is provided with a filler cap opening 20 adapted to threadedly receive a filler cap (not shown).

In FIG. 3 a conventionalmaster cylinder piston 22 and primary cup assembly 23 are shown disposed in the bore 14 of the master cylinder 12, the piston 22 being shown in its fully retracted position. A relatively large fluid passage 24 is provided in the cylinder wall portion 12a to provide fluid pressure communication between the fluid reservoir 16 and bore 14 to supply pressure fluid to the non-pressure generating portion of the bore during the protractile pessure generating stoke of the master cylinder piston 22. Pressure fluid also flows through passage 24 from the bore 14 to the reservoir 16 during the retraction or pressure releasing stroke of piston 22. A- fluid pressurev compensation port hole or vent port, with which the present invention is particularly concerned, is shown at 26 extending through the cylinder wall portion 120: to permit fluid communication between the reservoir 16 and pressure generating portion of the bore 14 when the piston 22 is in its retracted position. The functions of a compensation port hole, such as the port hole 26, were previously fully described herein.

As will be explained in greater detail hereinafter, the fluid pressure compensation port hole 26 is provided in the cylinder wall portion 12a by forming a recess, indicated in the drawings at 26a, in order to reduce the thickness of the wall a predetermined amount at the location where it is desired to provide the port hole, and then perforating the remaining or reduced section of the wall at that location to complete the port hole. The formation of the recess provides a cylinder wall section of reduced thickness, as indicated at 12b in FIGS. 1 and 2, to permit or facilitate the perforating operation where the original cylinder wall thickness is too great to suitably perforate or punch. A novel punching apparatus for performing the abovementioned perforating operation is indicated generally at 28 in FIGS. 1 and 2.

As seen in FIGS. 1 and 2, the master cylinder housing 10 is disposed on the punching apparatus 28, which in turn, is mounted to an actuating mechanism 30 adapted to operate the punching apparatus. The actuating mechanism 30 is secured to a base or supporting table 31, such as by bolts 32.

The punching apparatus 28 includes a cylindrical, punch-carrying housing or sleeve member 34 which is slidingly received in the bore 14 of the master cylinder 12 when the housing 10 is disposed on the punching apparatus. The sleeve member 34 is provided with a cylindrical bore 36 which guides a cylindrical punch actuating member 38 disposed therein and which is adapted to engage and actuate a punching or perforating element 40. The upper end of the bore 36 is closed by a dust cap 39. The punching element 40 is slidable in a pair of diametrically opposed coaxial bores 42 and 44 extending through opposed side walls of the sleeve member 34. The axes of bores 42 and 44 are normal to the longitudinal or vertical axis of the sleeve member 34 so that the element 40 is guided by the bores 42 and 44 for movement in a radial direction. The punching element 40, as shown also in FIG. 4, includes a cylindrical punch holder 46 provided with a recess 47 in one end thereof, and a punch member 48 which is secured in the recess by a set screw 49. If desired, the holder 46 and punch member 48 may be integrally formed.

The punch member 48 has an annular punching or perforating portion 50 with a flat annular end surface 51 at the free end thereof, and an annular shoulder 52 which intersects the peripheral surface of the annular perforating portion 50 in a predetermined radius at 53. With this construction, the punch member 48 is provided with an annular peening surface between the perforating portion 50 and the shoulder 52 so that during a punching operation when the perforating portion 50 enters the material it is perforating, the annular peening surface formed at the radius 53 will engage and peen the material at the inner mouth of the punched .port hole so that the inner mouth or edge of the hole will be smoothly rounded, as will be pointed out hereinafter.

In the illustrated embodiment, the punch actuating member 38 is provided with a cam member 55 at the upper end thereof which cooperates with a cam groove or slot 56 formed in the punching element 40 to impart motion to the element 40 during punching operations. The groove 56, as more clearly seen in FIGS. 4 and 5, is formed in one side of the punching element and extends angularly across the element. The groove 56 has opposed side walls 57 and 58. The side wall 57 of the groove extends across the element in a plane at a predetermined angle to the longitudinal axis of the punching element. A wall portion 58b also extends in a plane at a predetermined angle to the longitudinal axis of the element, and is shown parallel to the plane of wall 57. Side wall 57 and wall portion 58b of the groove serve as cam surfaces which cooperate respectively with opposite side walls 59 and 60 on the cam member 55, as seen in FIG. 7, to effect reciprocal movement of the punching element 40 when the actuating member 38 is reciprocated in bore 36. Each of the walls 59 and 60 of cam member 55, which walls serve as cam surfaces, is formed in a plane at an angle to the longitudinal axis of the punch actuating member 33, and such that these walls are angularly complementary to the wall 57 and wall portion 58b, respectively, on'the punching element 48. As seen also in FIGS. 6 and 7, cam member 55 has an inner flat side 62 which slidably engages the flat bottom of groove 56 of the element 40 and an opposed outer arcuate wall 64 ghich slidingly engages the bore 36 of the housing memer 34.

Wall portion 58a, which is in a plane perpendiuclar to the longitudinal axis of the punching element, provides the groove 56 with an enlarged entranceway to permit insertion of the cam member 58 into the groove in assembling the punching apparatus and removal therefrom for disassembling the apparatus.

The cam member 55 of the punch actuating member 38 cooperates with the groove 56 in punching element 40 to move the punching element in a work-producing or punching direction from a leftward position to the right in response to an upwardly directed force applied to the actuating member 38, as viewed in FIGS. 1 and 2, and to return or move the punching element 40 to the left from a rightward position in response to a downward force applied to the actuator 38. A return spring 66 is disposed in a counterbore 68 formed in the lower end of the sleeve member 34 between the shoulder provided by the counterbore and a flange 70 provided on the punch actuating member 38 to effect a return of the punching element 40 after it has been moved to the right or in a punching direction.

While various types of devices can be employed which will suitably actuate the punching apparatus 28, the mechanism 30 illustrated in the drawings includes a housing 72 having an upstanding portion 74 with an upper flange 76 to which a flange 78 on the sleeve member 34 is attached, as by bolts. A vertically extending bore 80 is provided in the upstanding portion of the housing for slidably receiving an actuating piston 82, the upper end of which is shown in engagement with the lower end or flange 70 of the punch actuating member 38. The housing 72 is also provided with a horizontally extending bore 84 connecting with the vertical bore 80. Disposed in the bore 84 is another actuating piston 86 adapted to have a force applied thereto for actuating the punching apparatus.

The piston 86 is provided with a groove 88 having a wall 90 in a plane perpendicular to the longitudinal axis of the piston 86 and a wall 92 in a plane which is inclined at a predetermined angle to the longitudinal axis of the piston and the plane of wall 90. Actuating piston 82 has a lower end wall 94 in a plane inclined at an angle to the longitudinal axis of the piston 82. The lower end wall 94 of the piston 82 and the wall 92 of the piston 86 are formed in planes at complementary angles so as to serve as cooperating cam surfaces by which motion is transmitted from the piston 86 to the piston 82 in response to a force applied to the right-hand end of the piston 86.

A return spring 97 for the piston 86 is disposed between the housing 72 and a collar member 98 which threadedly receives an end portion of piston 86. A force receiving screw member 100 is shown threaded into the end of piston 86 and in engagement with the collar 98. A force for actuating the driving mechanism 30 and the punching apparatus 28 is applied to the head of screw member 100, for example, by a fluid pressure motor, such as a conventional pneumatic power cylinder or the like, having a force applying actuator such as indicated at 102. The actuator 102 is adapted to move leftwardly, as viewed in FIG. 1 of the drawings, into engagement with screw member 100 for moving the primary piston 86. The collar member 98 provides means for preadjusting the driving mechanism so as to obtain a desired predetermined length of stroke for the pistons 86 and 82 so as to obtain a desired length of stroke for the punch actuating member 38 and punching element 40. Screw member 100 engages the free end of the collar 98 and thereby serves to lock the collar in its adjusted position.

When the master cylinder housing is placed on the punching apparatus, the cylinder 12 slides downwardly over the sleeve member 34 until the lower end thereof engages the upper side of fiange 78. This engagement locates the housing 10 relative to the punching element 40 in an axial direction, that is, so that the punching element 40 is at a predetermined axial distance from the ends of the cylinder. In order to suitably position the master cylinder housing 10 circumferentially of the punching apparatus, an indexing member 104, shown as a generally C-shaped plate, is secured as by bolts to the housing 72 of the driving mechanism 30. Plate 104 is provided with an indexing pin 106, shown as a dowel pin, secured in an opening formed in the plate 104. The indexing pin 106 extends vertically upwardly from plate 104 and is predeterminately located thereon so that when the master cylinder housing 10 is placed on the punching apparatus the pin 106 will enter one of the mounting holes 19 of the master cylinder mounting flange 18 and accurately locate the housing 10 circumferentially of the punching element 40. In this way, the housing 10 is predeterminately positioned on the punching apparatus 28 so that the compensation port hole 26, when formed therein, will be accurately disposed in the bore at the desired location.

As is apparent from the drawings, the sleeve member 34 has an outer diameter which is only slightly less than the diameter of the cylinder bore 14 so that the sleeve member will be in close-fitting relation with the walls of the cylinder bore 14. Thus, when the housing 10 is positioned on the punching apparatus, as previously described herein, the bore or cylinder wall portion 12a will lie against or be closely adjacent the outer peripheral surface of the sleeve member with the reduced wall section 12b, to be perforated, adjacent the radially outer end of the bore 44 and in position to be struck by the punching element 40.

Preferably, the recess 26a is formed by drilling such as by employing the drill shown in phantom at 110 in FIG. 1 and while the housing 10 is disposed on the punching apparatus 28. The drill 110 may be mounted to a conventional drill fixture (not shown) which is operable to move the drill 110- into and out of the reservoir 16. With such an arrangement, the drill fixture may be predeterminately located and arranged relative to the punching element 40 so that after the housing 10 in FIG. 1 is predeterminately positioned on the punching apparatus, drill 110 may be moved into the reservoir 16 through the filler cap opening 20 and used to drill radially inwardly into the wall portion 12a of the cylinder to form the recess 26a in aligned relation with the punching element 40. The drill 110, after the recess has been for-med, may then be retracted from the reservoir.

After the recess 26a is formed in the wall portion 12a of the cylinder, the punching apparatus is then actuated so as to perforate or punch the reduced wall section 12b. When piston 102 engages the screw member 100, the piston 86 is moved leftwardly causing piston 82 to move upwardly because of the cooperating cam surfaces 92 and 94 on these pistons. The piston 82, in turn, moves the actuating member 28 upwardly whereby the cam member 55 slides upwardly in the groove 56 of the punching element 40 to effect movement of the punching element to the right or radially outwardly to perforate the reduced wall section 12b of the cylinder wall portion 12a. This movement of punching element 40 to the right or in its punching direction is effected by the cooperating walls 59 and 57 on cam member 55 and element 40, respectively. As is apparent from drawings, the perforating portion 50 of element 40 when actuated moves out of 'bore 44 or past the outer peripheral surface of the sleeve member 34 to punch an opening in the wall section 12b which is disposed adjacent the outer surface of said sleeve member and at the radially outer end or mouth 44a of the bore 44.

FIG. 2 shows the apparatus in an actuated position with the punching element 40 moved to the right and having perforated the reduced wall section 12b of wall portion 12a. The punching element 40 forms the opening 26b, as shown in FIG. 8, which connects with the recess 26a to thereby form the completed compensating port hole 26. During the punching stroke of the punching element 40, the inner mouth of the port hole is struck by the peening surface provided by the radius 53 of shoulder 52 of the punch member 48, as is apparent from FIG. 2. In this way, the inner mouth or edge of the opening formed by the punching element is peened inwardly of the opening during the punching operation to provide the port hole 26 with a smoothly rounded inner mouth, as indicated at 112 in FIG. 8. The inner mouth of the port hole will thus be free from burrs and sharp edges.

When the actuator 102 is retracted from its position shown in FIG. 2, spring 97 returns the piston 86 to its unenergized position allowing spring 66 to return the actuating member 38 and punching element 40 to their unenergized positions shown in FIG. 1. The cam surfaces 58b and 60 on the element 40 and cam member 55, respectively, cooperate to return the element 40 back to its unenergized position. The housing 10 may then be removed from the punching apparatus by sliding it upwardly ofi the sleeve member 34, and the punching apparatus will be in condition for receiving another master cylinder housing to be perforated.

In FIG. 9, a modified form of recess, as indicated at 26'a, is shown formed in the wall 12'a of a master cylinder. The recess 26'a is formed so as to have a substantially flat bottom surface 114 to provide a reduced Wall section 12'b of substantially constant width or thickness. The area of the wall section 12'!) is shown in FIG. 6 as appropriately equal to the area of the end surface 51 of the punching element 40 although it may be of larger area if desired. Because wall section 12'!) is of substantially constant thickness, punching element 4!} does not have to pass through as much material in perforating the cylinder wall as it does in the case where the bottom surface of the recess is formed with a conical bottom surface, such as in the case of recess 26a in FIG. 1. For this reason, the material of wall section 12'a presents less resistance to perforation by the punching element and thereby increases the life expectancy of the punching element and decreases the danger of punch breakage. Also, the location of recess 26'a relative to the punching element is not as critical.

From the foregoing, it is now apparent that a novel method and apparatus for forming a passageway through the wall of a fluid pressure cylinder meeting the objects set out hereinbefore are provided and that changes or modifications to the method and apparatus set forth in the disclosure by way of illustration may he made by those skilled in the art without departing from the true spirit of the invention as defined in the claims which follow.

What I claim is:

1. A method of forming a port hole through the metal wall of a cylinder having an outer surface, and an inner surface defining a bore comprising the steps of providing a recess in the wall of the cylinder which extends from the outer surface of the cylinder inwardly a predetermined distance toward the inner surface of the cylinder to provide a relatively thin wall section of substantially reduced thickness, and then punching said wall section with a punch from the bore side of the cylinder to provide an opening connecting with the recess.

2. A method of forming an opening through the metal side wall of a cylinder having an outer surface, and an inner surface defining a bore comprising the steps of drilling a recess of predetermined depth in the side wall from the outer surface of the cylinder to provide a relatively thin wall section of substantially reduced thickness, and then punching said wall section with a punching element from the bore side of the cylinder to provide an opening connecting with the recess.

3. A method of forming a port hole through a metal wall portion of a bore in a fluid pressure generating cylinder having a reservoir partitioned from the bore of the cylinder by the wall portion comprising the steps of inserting a drill into the reservoir and drilling radially inwardly into the wall portion a predetermined distance to provide a relatively thin wall section of substantially reduced thickness, and driving a punching element into the wall section from the bore side of the wall portion to provide a port hole through the wall potrion.

4. A method of forming a port hole through a metal wall portion of a bore in a fluid pressure generating cylinder having a reservoir partitioned from the bore by the Wall portion comprising the steps of inserting a drill into the reservoir and drilling inwardly of the cylinder into the wall portion a predetermined distance to provide a relatively thin wall section of substantially reduced thickness, and driving a punching element, having a leading perforating portion intersecting a shoulder on the punching element in a radius, into the wall section from the bore side of the wall portion with the radius engaging the wall section to provide an opening connecting with the recess and having an inner mouth peened by the radius on the punching element.

5. A method of forming a port hole through the metal side wall of a bore in a cylinder comprising the steps of providing a punching apparatus including a sleeve memher having a diameter slightly less than the diameter of punching apparatus with the sleeve member and punching element disposed within the cylinder bore, drilling a recess of predetermined depth in the side wall of the cylinder from the outer surface thereof in aligned relation with said punching element to provide a relatively thin wall section of substantially reduced thickness, applying a force to said punching element to drive said punching element into said wall section to form an opening connecting with the recess, and retracting the punching element from the opening formed thereby.

6. A method of forming a port hole through the metal wall of a fluid pressure generating cylinder having an outer surface, and an inner surface defining a bore comprising the steps of forming a recess in the wall of the cylinder having a substantially fiat bottom and which extends inwardly from the outer surface of the cylinder a predetermined distance to provide a relatively thin wall section of substantially reduced thickness having a substantially constant cross-section, and then punching said wall section with a punch from the bore side of the cylin der to form an opening connecting with the recess.

7. A method of forming a port hole through a metal wall portion of a fluid pressure generating cylinder having a bore and a fluid reservoir partitioned from the bore by the wall portion comprising the steps of providing a recess in the wall portion which extends from the reservoir side of the wall portion a predetermined distance toward the bore to provide a relatively thin wall section of substantially reduced thickness, and then punching said wall section with a punch from the bore side of the wall portion toward the reservoir side thereof to provide an opening in the wall section connecting with the recesss.

8. A method of forming a port hole through the metal side wall of a cylinder having an outer surface and an inner surface defining a bore comprising the steps of providing a punching apparatus including a punch carrying member having a movable punch for punching engagement with the side wall of the cylinder, forming a recess in the side wall of the cylinder which extends from the outer surface thereof inwardly a predetermined distance toward the inner surface thereof to provide a relatively thin wall section of substantially reduced thickness, positioning the cylinder on the punching apparatus with the punch carrying member and punch within the cylinder bore and with said wall section in aligned relation with the punch, and then applying a force to the punch to drive the punch into said wall section to form an opening therein connecting with the recess.

9. A method of forming a port hole through the metal wall of a cylinder having an outer surface and an inner surface defining an axial bore comprising the steps of providing a recess in the cylinder wall which extends from the outer surface thereof substantially radially inwardly a predetermined distance toward the inner surface thereof to provide a relatively thin wall section of substantially reduced thickness, providing a punching element having a leading perforating portion and a shoulder intersecting the perforating portion in substantially a radius, and then driving the perforating portion into said wall section from the bore side of the cylinder wall to form an opening in said wall section connecting with the recess and said radius into engagement with the mouth of said opening onthe bore side of the cylinder wall to peen said mouth.

10. A method of forming a port hole through a metal side wall of a cylinder having an outer surface and an inner surface defining an axial bore comprising the steps of providing a punching apparatus including a punch carrying member having a movable punching element adapted to fit within the cylinder bore, said punching element having a leading perforating portion for punching engagement with said side wall and an anuular shoulder intersecting the perforating portion in substantially a radius, positioning said cylinder on said apparatus with the punch carrying member and punching element predeterminately positioned within the cylinder bore, then forming a recess in said side wall in aligned relation with said perforating portion with the recess extending from the outer surface of said side wall substantially radially inwardly a predetermined distance toward the inner surface of said side wall to provide a relatively thin wall section of substantially reduced thickness, and then applying a force to said punching element to drive said perforating portion in a radially outward direction into said wall section to form an opening therein connecting with the recess and said radius into peening engagement with the mouth of said opening at the inner surface of said side wall to peen said mouth.

11. The method according to claim 10 wherein said recess is formed such that said wall section has a substantiaily constant thickness.

12. A method of forming a port hole through a metal wall portion of a fluid pressure cylinder having a bore and a pressure fluid reservoir partitioned from the bore by the wall portion comprising the steps of providing a punching apparatus including a punch carrying member having a movable punching element adapted to fit Within the cylinder bore, said punching element having a leading perforating portion for punching engagement with the wall portion and an annular shoulder intersecting the perforating portion in substantially a radius, positioning said cylinder on said apparatus with the punch carrying member and punching element predeterminately positioned within the cylinder bore, then inserting a drill into said reservoir and drilling a recess in the wall portion in aligned relation with said perforating portion of the punching element with the recess extending from the reservoir side of the wall portion inwardly a predetermined distance toward the bore side of the wall portion to provide a relatively thin wall section of substantially reduced thickness, and then applying a force to said punching element to drive said perforating portion into said wall section to form an opening therein connecting with said recess and said radius into peening engagement with the mouth of said opening on the bore side of the wall portion to peen said mouth.

13. A method of forming a port hole through the metal wall of a hollow workpiece having an outer surface, and an inner surface defining a bore comprising the steps of providing a recess in the wall of the workpiece which extends from the outer surface of the workpiece inwardly a predetermined distance toward the inner surface of the workpiece to provide a relatively thin wall section of substantially reduced thickness, and then punching said wall section with a punch from the bore side of the workpiece to provide an opening connecting with the recess.

14. A method of forming a port hole through the metal side wall of a hollow work-piece having an outer surface and an inner surface defining a bore comprising the steps of providing a punching apparatus including a punch carrying member having a movable punch for punching engagement with the side wall of the workpiece, forming a recess in the side wall of the workpiece which extends from the outer surface thereof inward-1y a predetermined distance toward the inner surface thereof to provide a relatively thin wall section of substantially reduced thickness, positioning the workpiece on the punching apparatus with the punch carrying member and punch within the work-piece bore and with said wall section in aligned relation with the punch, and then applying a force to the punch to drive the punch into said wall section to form an opening therein connecting with the recess.

References Cited by the Examiner UNITED STATES PATENTS 37,189 12/1862 Westlake 29-566 295,090 3/1884 Whitman 83-191 750,746 l/1904 Woodburn 8.3-191 1,432,073 10/1922 Lowy 83-191 1,549,462 8/1925 De Wyk 83-191 1,920,303 8/1933 Grotnes 83-191 2,727,256 12/1955 Moore 10-10 2,737,831 3/1956 Webb 76-107 2,887,694 5/1959 Sauter 10-27 2,972,779 2/ 1961 Cowley 83-54 3,037,277 6/1962 Pauls 29-545 3,123,910 3/ 1964 Neilson 29-545 3,141,358 7/1964 Burke 76-107 FOREIGN PATENTS 795,211 3/ 1936 France.

ANDREW R. JUHASZ, Primary Examiner. WILLIAM W. DYER, JR., Examiner. J. L. SEITCHIK, Assistant Examiner. 

1. A METHOD OF FORMING A PORT HOLE THROUGH THE METAL WALL OF A CYLINDER HAVING AN OUTER SURFACE, AND AN INNER SURFACE DEFINING A BORE COMPRISING THE STEPS OF PROVIDING A RECESS IN THE WALL OF THE CYLINDER WHICH EXTENDS FROM THE OUTER SURFACE OF THE CYLINDER INWARDLY A PREDETERMINED DISTANCE TOWARD THE INNER SURFACE OF THE CYLINDER TO PROVIDE A RELATIVELY THIN WALL SECTION OF SUBSTANTIALLY REDUCED THICKNESS, AND THEN PUNCHING SAID WALL SECTION WITH A PUNCH FROM THE BORE SIDE OF THE CYLINDER TO PROVIDE AN OPENING CONNECTING WITH THE RECESS. 